Composition and method for treating or preventing skeletal muscle fibrosis

ABSTRACT

A compound in combination with a pharmaceutically acceptable carrier, the compound having a formula: wherein: R 1  is a member of the group consisting of hydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy; R 2  is a member of the group consisting of hydroxy, acetoxy, and lower alkoxy; and R 3  is a member of the group consisting of hydrogen and lower alkenoxy-carbonyl; and n is either 1 or 2; and pharmaceutically acceptable salts thereof; for use in treatment of or prevention of skeletal muscle fibrosis and/or for inducing skeletal muscle regeneration.

RELATED APPLICATIONS

This application is a continuation of and claims priority under 35U.S.C. §120 to U.S. Ser. No. 13/782,325, entitled COMPOSITION AND METHODFOR TREATING OR PREVENTING SKELETAL MUSCLE FIBROSIS filed on Mar. 1,2013, which claims priority from U.S. National application Ser. No.12/523,954 entitled COMPOSITION AND METHOD FOR TREATING OR PREVENTINGSKELETAL MUSCLE FIBROSIS filed on Feb. 15, 2010, which is the NationalStage Entry of PCT/IL08/00088 filed Jan. 21, 2008, which claims priorityfrom U.S. Provisional Application Ser. No. 60/885,896 entitledCOMPOSITION AND METHOD FOR TREATING OR PREVENTING SKELETAL MUSCLEFIBROSIS filed Jan. 21, 2007.

FIELD OF THE INVENTION

The present invention relates to a method of treating fibrosis, and moreparticularly to treatment, prevention or amelioration of skeletal musclefibrosis by use of halofuginone or related compounds.

BACKGROUND OF THE INVENTION

Muscle fibrosis is a phenomenon that frequently occurs in diseased ordamaged muscle. It is characterized by the excessive growth of fibroustissue, which usually results from the body's attempt to recover frominjury. Fibrosis impairs muscle function and causes weakness. The amountof muscle function loss generally increases with the extent of fibrosis.Fibrosis is usually progressive and can contribute to the patient'sinability to carry out ordinary tasks of independent living, such asgrasping objects or walking. Fibrosis commonly occurs as a result ofmuscular dystrophy, as well as due to other afflictions, such asdenervation atrophy, a degradation of muscle tissue caused by loss ofneural contact to a muscle. For some types of muscular dystrophy, suchas Duchenne, fibrosis can result in death as the muscles of thediaphragm are affected (the diaphragm is a skeletal muscle which isinvoluntary rather than voluntary).

Muscular dystrophies are a heterogeneous group of genetic disorderscharacterized by the progressive loss of muscle strength and integrity.Dystrophic muscle shows variation in muscle fiber size, infiltration ofconnective and fatty tissue, and centrally located nuclei. The membranesof the fibers are fragile and extensive damage occurs, leading tonecrosis and muscle wasting.

Victims of muscular dystrophies, particularly Becker muscular dystrophy(BMD) and Duchenne muscular dystrophy (DMD), frequently suffer fromincreasing skeletal muscle fibrosis as the disease progresses.

The most common form of muscle dystrophy is the X-linked recessive DMD,a severely penetrating allelic manifestation which affects 1 in 3500live males at birth; about a third of cases occur as de novo mutationsin the infant (Emery A E. (1991) Neuromusc. Disord. 1: 19-29).

Usually the disease is diagnosed at 4-5 years of age and by 8-10 years,deterioration of the patient's condition necessitates wheelchair use. Bytheir early teens, further neurological and cardiological symptoms areapparent. Progression of muscle degeneration and worsening clinicalsymptoms, lead to death in the late teens or early twenties, typicallyas a result of cardio-pulmonary complications due to fibrosis of thediaphragm.

The leading causes of death in DMD victims, respiratory and heartfailure, result from weakness in diaphragm and myocardium muscles thatare most affected by fibrosis (Finsterer, (2003) Cardiology 99:1-19).Fibrosis is characterised by an increase in extra-cellular matrix (ECM)constituents especially collagen type I. Both in DMD and Congenitalmuscular dystrophy (CMD), an increase in type I and III collagens wereobserved in the skeletal muscle (Hantai et al. (1985) Connect TissueRes. 13:273-81 and Dunace, et al. (1980) Nature 284:470-472) leading tofibrosis, which correlated with muscle destruction (Zhao, et al. (2003)J. Patho. 201:149-59). The cardiac involvement in DMD is characterizedpathologically by degeneration and fibrosis of the myocardium, probablydue to myofibroblast activity, centering around the posterolateral wallof the left ventricle.

BMD is a less severe condition than DMD, characterized by slowlyprogressive muscle weakness of the legs and pelvis, again due tofibrosis of the muscles (although for BMD the skeletal muscles are moregreatly affected). The advance of fibrosis often causes ever greaterloss of mobility and a reduced life expectancy. At some point, thepatient may become too weak to walk and takes to a wheelchair.

Both BMD and DMD are associated with defects in the dystrophin gene, thegene responsible for the production of dystrophin protein, which is avital part of the dystrophin-glycoprotein complex. DMD is characterizedby the near absence of dystrophin protein in skeletal muscles, while BMDresults from different mutations in the same gene, resulting indecreased or damaged dystrophin. The presence of some dystrophinprotects the muscles of those with BMD from degenerating as badly or asquickly as those of DMD victims.

The dystrophin-glycoprotein complex connects the actin cytoskeleton ofmyofibres to the extracellular matrix (ECM) and is therefore integral tothe contractile structure of muscle (Yue Y, et al. (2003) Circulation,108:1626-32 and Michele et al. (2003) J. Biol. Chem 278:15457-60). Thepreliminary stage of DMD is characterized by the presence of focalgroups of necrotic myofibres, muscle hypertrophy and abnormally highlevels of muscle creatine kinase (CK). In the pathological phase,repeated cycles of degeneration exhaust the regenerative capacity ofmuscle-specific progenitor cells (satellite cells) and fibroticmechanisms cause the progressive replacement of the muscle tissue withcollagenous connective tissue (Rafael et al., 1997). These processeslead to joint contraction, loss of ambulation and death from respiratoryor cardiac failure (Wells, et al. (2002) Neuromuscle Disord. 12 Suppl1:S11-22).

The perfect solution for DMD and BMD patients would be to place a normalcopy of the dystrophin gene into muscle cells, and hence restoresufficient protein expression to improve structure and function(Khurana, et al. (2003) Nat Rev Drug Discov. 2:379-90). At 3.0 MB thedystrophin gene is vast, and successful therapy would require massiveand sustained gene transfer (Hoffman, et al. (1987) Cell 51:919-28 andSkuk, et al. (2002) Curr. Opin. Neurol. 15:563-9 and Thioudellet, et al.(2002) Neuromuscul Disord. 12 Suppl 1:S49-51). Muscle fibrosis is amajor obstacle in gene therapy since it hampers gene delivery.

An alternative to replacing the faulty gene is to modulate itsexpression by employing antisense oligonucleotides that alter RNAstability, or splicing (Lu Qi, et al. (2003) Nat. Med. 9(8):1009-14 andRando T A. (2002) Am. J. Phy. Med. Rehabil. 81(11Suppl):S175-86),thereby resulting in the production of a functional protein.Transplantation of muscle precursor cells (myoblast transfer) has alsobeen explored as a method for restoring dystrophin protein to dystrophicmuscle (Law P K et al. (1997) Transplant Proc. 29(4):2234-7). Thistechnique is constrained by the difficulties associated with treatinglarge volumes of muscle with long-lasting effect. An alternativeapproach is to up-regulate the expression of an endogenous protein thateffects some functional replacement (Krag T O, et al. (2001) ActaPhysiol Scand. 171:349-58). However, all of these treatments areineffective unless the progression of the underlying fibrotic conditioncan be halted or at least ameliorated somewhat.

The crucial role of collagen in fibrosis has prompted attempts todevelop agents that inhibit or modulate its accumulation. Several uniquepost-transcriptional enzymes of the collagen biosynthesis pathway appearto be attractive targets for reducing the formation of collagen fibersor for the accumulation of fibers with altered properties (Prockop D J,(1995) Annu Rev Biochem. 64:403-34).

The major disadvantage of these inhibitors is that they are notcollagen-type specific and may inhibit the biosynthesis of othercollagens with serious toxic consequences.

To date there is no effective therapy for reducing skeletal musclefibrosis. No treatment which affects fibrotic tissue without adverselyaffecting healthy muscle tissue or other body functions is currentlyknown. The only treatment to have shown clinical efficacy is aprednisone/prednisolone treatment that results in a modest increase instrength, and delays, but does not halt, the progress of the disease(Backman, et al. Neuromuscul Disord. 5:233-41 and Dubowitz, (2002)Neuromuscul Disord. 12:113-6).

There is thus a widely recognized need for, and it would be highlyadvantageous to have, a method of preventing or retarding the build upof skeletal muscle fibrosis that accompanies disorders such as Duchenneand Becker muscular dystrophies and other muscle dystrophies withextensive fibrosis, as well as to reduce the effect on muscles of thediaphragm for Duchenne muscular dystrophy.

Quinazolinone Derivatives

Quinazolinone derivatives were first taught in U.S. Pat. No. 3,320,124to American Cyanamid as a treatment for the intestinal parasiticdisease, coccidiosis. Halofuginone,(7-bromo-6-chloro-3-[3-(3-hydroxy-2-piperidinyl)-2-oxopropyl]-4(3H)-quinazolinone),an analog of a plant alkaloid originally isolated from the plant Dichroafebrifuga, was described as the preferred quinazolinone derivative.Subsequently, U.S. Pat. Nos. 4,824,847; 4,855,299; 4,861,758 and5,215,993 all relate to the coccidiocidal properties of halofuginone.

More recently, it was disclosed in U.S. Pat. No. 5,449,678 that thesequinazolinone derivatives are unexpectedly useful for the treatment of afibrotic condition such as scleroderma and graft-versus-host disease(GVHD). This disclosure provided compositions of a specific inhibitorcomprising a therapeutically effective amount of a pharmaceuticallyactive compound of the formula:

wherein: n=1-2R₁ is a member of the group consisting of hydrogen, halogen, nitro,benzo, lower alkyl, phenyl and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy and loweralkoxy; andR₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl.Pharmaceutically acceptable salts thereof are also included. Of thisgroup of compounds, halofuginone has been found to be particularlyeffective for the disclosed treatment.

The clinical potential of halofuginone in anti-fibrotic therapy has alsobeen described in Pines, et al. Drug of the Future 21:569-599 and Pines,et al. (1997) Gen. Pharmaco. 30:445-450 and Pines, et al. (2000) DrugDevelop. Res. 50, 371-378). Halofuginone, an inhibitor of collagen typeI synthesis has been found to inhibit the gene expression of collagentype 1, but not of type II (Granot, et al. Biochim Biophys Acta 1156:107-112) or type III (Choi, et al. (1995) Arch Surg 130:257-261).

U.S. Pat. No. 5,891,879 further discloses that the quinazolinonederivatives are effective in treating restenosis. The twoearlier-described conditions, scleroderma and graft-versus-host disease,are associated with excessive collagen deposition, which can beinhibited by halofuginone. Restenosis is characterized by smooth musclecell proliferation and extracellular matrix accumulation within thelumen of affected blood vessels in response to a vascular injury (Choiet al., Arch. Surg., 130:257-261 (1995)). One hallmark of such smoothmuscle cell proliferation is a phenotypic alteration, from the normalcontractile phenotype to a synthetic one. Type I collagen has been shownto support such a phenotypic alteration, which can be blocked byhalofuginone (Choi et al., Arch. Surg., 130: 257-261, (1995); U.S. Pat.No. 5,449,678).

Notably, the in vitro action of halofuginone does not always predict itsin vivo effects. For example, as demonstrated in U.S. Pat. No.5,449,678, halofuginone inhibits the synthesis of collagen type I inbone chrondrocytes in vitro. However, chickens treated with halofuginonewere not reported to have an increased rate of bone breakage, indicatingthat the effect is not seen in vivo. In addition, even thoughhalofuginone inhibits collagen synthesis by fibroblasts in vitro, itpromotes wound healing in vivo (WO 01/17531). Thus, the exact behaviorof halofuginone in vivo cannot always be accurately predicted from invitro studies.

Quinazolinone-containing pharmaceutical compositions, includinghalofuginone, have been disclosed and claimed as effective for treatingmalignancies (U.S. Pat. No. 6,028,075), for prevention ofneovascularization (U.S. Pat. No. 6,090,814), as well as for treatinghepatic fibrosis (U.S. Pat. No. 6,562,829), pulmonary fibrosis (WO98/43642) and renal fibrosis (WO 02/094178), scleroderma and a varietyof other serious diseases, exhibit excessive production of connectivetissue, which results in the destruction of normal tissue architectureand function.

WO 00/09070 relates to a method for treating and preventing fibroticprocess, which results from pathophysiological responses to tissuetrauma, preferably cardiac fibrosis.

In most animal models of fibrosis, regardless of the tissue,halofuginone has a minimal effect on collagen content in thenon-fibrotic animals, whereas it exhibits a profound inhibitory effectin the fibrotic organs. This suggests a different regulation of the lowlevel house-keeping expression of collagen type I genes on the one handand the over-expression induced by the fibrogenic stimulus which isusually an aggressive and a rapid process, on the other.

Muscle Tissue

Muscle is a very specialized tissue that has both the ability tocontract and the ability to conduct electrical impulses. Muscles areclassified both functionally as either voluntary or involuntary, andstructurally as either striated or smooth. From this, there emerge threetypes of muscles: smooth muscle (involuntary), skeletal voluntary muscle(voluntary and involuntary) and cardiac muscle. Skeletal and cardiacmuscle are called striated muscle because of their striped appearanceunder a microscope.

Skeletal muscle may be of the voluntary or involuntary muscle type,being innervated by neurons that originate from the somatic or voluntarybranch of the nervous system, providing willful control of the skeletalmuscles, or, as in the case of the diaphragm muscles, being controlledby efferent nerves from the respiratory centre which pass down thespinal cord to the diaphragm. Skeletal muscle cells are longmulti-nucleated cylinders, which acquired this characteristic becausethey develop from the fusion of small single cells into long units. Thecells may vary in diameter, averaging between 100 and 150 microns.

Skeletal muscle cells are independent cells separated from one anotherby connective tissue and must each be stimulated by axons of a neuron.All the cells innervated by branches from the same neuron will contractat the same time and are referred to as a motor unit. Motor units varyin size: large motor units with more than 100 cells are typical of theslow acting postural muscles. Very small motor units with around 10cells or so are typical of fast acting muscles with very precise controlsuch as those which move the eye. Most human muscles have a mixture ofmotor units of different sizes.

Skeletal muscles have distinct stripes or striations that identify themand are related to the organization of protein myofilaments inside thecell. Skeletal muscle cells are associated with a type of stem cellknown as a satellite cell. These cells are believed to aid in recoveryof muscle fibers from damage and can contribute their nuclei to replaceand supplement the nuclei of the damaged cells. This occurs in responseto the “microtears” produced by strenuous exercise and results inincreased production of proteins and myofibrils.

Voluntary muscles comprise a variety of fiber types which arespecialized for particular tasks. Most voluntary muscles contain amixture of fiber types although one type may predominate.

Type 1 or slow oxidative fibers have a slow contraction speed and a lowmyosin ATPase activity. These cells are specialized for steady,continuous activity and are highly resistant to fatigue. Their motorneurons are often active, with a low firing frequency. These cells arethin (high surface to volume ratio) with a good capillary supply forefficient gas exchange. They are rich in mitochondria and myoglobin,which gives them a red color. They are built for aerobic metabolism andprefer to use fat as a source of energy. These are the marathon runner'smuscle fibers.

Type 2A or fast oxidative-glycolytic fibers have a fast contractionspeed and a high myosin ATPase activity. They are progressivelyrecruited when additional effort is required, but are still veryresistant to fatigue. Their motor neurons show bursts of intermittentactivity. These cells are thin (high surface to volume ratio) with agood capillary supply for efficient gas exchange. They are rich inmitochondria and myoglobin which gives them a red color. They are builtfor aerobic metabolism and can use either glucose or fats as a source ofenergy. These are general purpose muscle fibers which give the edge inathletic performance, but they are more expensive to operate than type1.

Type 2B or fast glycolytic fibers have a fast contraction speed and ahigh myosin ATPase activity. They are only recruited for brief maximalefforts and are easily fatigued. Their motor neurons transmit occasionalbursts of very high frequency impulses. These are large cells with apoor surface to volume ratio and their limited capillary supply slowsthe delivery of oxygen and removal of waste products. They have fewmitochondria and little myoglobin, resulting in a white color (e.g.chicken breast). They generate ATP by the anaerobic fermentation ofglucose to lactic acid. These are sprinter's muscle fibers, no use forsustained performance.

Cardiac muscle is the muscle found in the heart. It is composed of muchshorter cells than skeletal muscle that branch to connect to oneanother. These connections are by means of gap junctions calledintercalated disks that allow an electrochemical impulse to pass to allthe connected cells. This causes the cells to form a functional networkcalled a syncytium in which the cells work as a unit. Many cardiacmuscle cells are myogenic which means that the impulse arises from themuscle, not from the nervous system. This causes the heart muscle andthe heart itself to beat with its own natural rhythm. But the autonomicnervous system controls the rate of the heart and allows it to respondto stress and other demands. As such the heart is said to beinvoluntary.

The cardiac muscle has a number of unique features that reflect itsfunction of pumping blood.

-   -   The myofibrils of each cell (and cardiac muscle is made of        single cells—each with a single nucleus) are branched.    -   The branches interlock with those of adjacent fibers by adherens        junctions. These strong junctions enable the heart to contract        forcefully without ripping the fibers apart.    -   The action potential that triggers the heartbeat is generated        within the heart itself. Motor nerves (of the autonomic nervous        system) do run to the heart, but their effect is simply to        modulate—increase or decrease—the intrinsic rate and the        strength of the heartbeat. Even if the nerves are destroyed (as        they are in a transplanted heart), the heart continues to beat.    -   The action potential that drives contraction of the heart passes        from fiber to fiber through gap junctions.

Due to the numerous structural and functional differences betweenvarious muscle types, the effect of an active pharmaceutical ingredienton a particular muscle type cannot be predicted with any degree ofreliability according to the effect of that ingredient on a differentmuscle type.

SUMMARY OF THE INVENTION

The present invention successfully addresses the shortcomings of thepresently known methods of treating and/or preventing skeletal musclefibrosis by providing compositions and methods comprising aquinizolinone derivative.

As used herein, the quinazolinone derivative comprises a compound havinga formula:

wherein:

R₁ is a member of the group consisting of hydrogen, halogen, nitro,benzo, lower alkyl, phenyl, and lower alkoxy; R₂ is a member of thegroup consisting of hydroxy, acetoxy, and lower alkoxy; and R₃ is amember of the group consisting of hydrogen and lower alkenoxy-carbonyl;and n is either 1 or 2; and pharmaceutically acceptable salts thereof.

According to one aspect of the present invention there is provided apharmaceutical composition for treating and/or preventing and/or atleast reducing the rate of progression of skeletal muscle fibrosis in asubject in need thereof, the composition comprising a pharmaceuticallyeffective amount of a quinizolinone derivative and pharmaceuticallyacceptable salts thereof; and a pharmaceutically acceptable carrier.

According to another aspect of the present invention there is provided apharmaceutical composition for improving skeletal muscle regeneration ina subject in need thereof, the composition comprising a pharmaceuticallyeffective amount of a quinazolinone derivative and pharmaceuticallyacceptable salts thereof; and a pharmaceutically acceptable carrier.

According to yet another aspect of the present invention there isprovided a method for reducing the progression of skeletal musclefibrosis in a subject in need thereof, the method comprisingadministering a pharmaceutically effective amount of a quinazolinonederivative and pharmaceutically acceptable salts thereof; and apharmaceutically acceptable carrier.

According to still another aspect of the present invention there isprovided a method for improving and/or inducing skeletal muscleregeneration in a subject in need thereof, the method comprisingadministering a pharmaceutically effective amount of a quinazolinonederivative, and pharmaceutically acceptable salts thereof; and apharmaceutically acceptable carrier. The improving of skeletal muscleregeneration optionally occurs through inhibiting the TGFβ pathwayand/or by inhibiting the Myostatin Smad3-dependent pathway.

According to an additional aspect of the present invention there isprovided the use of a quinazolinone derivative, and pharmaceuticallyacceptable salts thereof; in the manufacture of a medicament forreducing the progression of skeletal muscle fibrosis in a subject inneed thereof.

According to further features in preferred embodiments of the inventiondescribed below, quinazolinone derivative is optionally and preferablyhalofuginone.

According to still further features in the described preferredembodiments, the subject in need of treatment by the compositions andmethods of the present invention is suffering from a disorder whichtargets skeletal muscle tissue, such as, for example muscular dystrophy,including Duchenne muscular dystrophy, Becker muscular dystrophy,Emery-Dreifuss Muscular Dystrophy, Limb-Girdle Muscular Dystrophy,Facioscapulohumeral Muscular Dystrophy, Myotonic Dystrophy,Oculopharyngeal Muscular Dystrophy, Distal Muscular Dystrophy, andcongenital muscular dystrophy.

Alternatively, the subject may be suffering from denervation atrophy.

Optionally, the skeletal muscle tissue targeted by the disorder maycomprise diaphragm muscle.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

The term “comprising” means that other steps and ingredients that do notaffect the final result can be added. This term encompasses the terms“consisting of” and “consisting essentially of.”

The phrase “consisting essentially of” means that the composition ormethod may include additional ingredients and/or steps, but only if theadditional ingredients and/or steps do not materially alter the basicand novel characteristics of the claimed composition or method.

The term “method” refers to manners, means, techniques and proceduresfor accomplishing a given task including, but not limited to, thosemanners, means, techniques and procedures either known to, or readilydeveloped from known manners, means, techniques and procedures bypractitioners of the chemical, pharmacological, biological, biochemicaland medical arts.

The term “active ingredient” refers to a pharmaceutical agent includingany natural or synthetic chemical substance that subsequent to itsapplication has, at the very least, at least one desired pharmaceuticalor therapeutic effect.

The term “therapeutically effective amount” or “pharmaceuticallyeffective amount” denotes that dose of an active ingredient or acomposition comprising the active ingredient that will provide thetherapeutic effect for which the active ingredient is indicated.

As used herein, the term “pharmaceutically acceptable” means approved bya regulatory agency of the Federal or a state government or listed inthe U.S. Pharmacopeia or other generally recognized pharmacopeia for usein animals, and more particularly in humans. Herein, the phrases“physiologically suitable carrier” and “pharmaceutically acceptablecarrier” are interchangeably used and refer to an approved carrier or adiluent that does not cause significant irritation to an organism anddoes not abrogate the biological activity and properties of theadministered conjugate.

As used herein, the term “carrier” refers to a diluent, adjuvant,excipient, or vehicle with which the therapeutic is administered.

Herein the term “excipient” refers to an inert substance added to apharmaceutical composition to further facilitate processes andadministration of the active ingredients.

As used herein, the singular form “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this disclosure, various aspects of this invention can bepresented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals there between.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 shows the effect of halofuginone on fibrosis and myogenesis viaSmad3-dependent pathways;

FIG. 2 presents the results of Sirius red staining for collagen contentand in situ hybridization of collagen al (I) gene expression in Mdx miceand C57B control mice, in the presence and absence of halofuginone;

FIG. 3 is a bar chart demonstrating the effect of halofuginone on musclefibrosis using staining and quantification by Image analysis; and

FIG. 4 is a bar chart illustrating muscle regeneration afterhalofuginone treatment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a method and pharmaceutical composition fortreating or preventing skeletal muscle fibrosis in a subject, or atleast reducing the progression thereof, by using a quinazolinonederivative, preferably halofuginone. According to preferred embodiments,the present invention relates to a method and pharmaceuticalcompositions for at least reducing the progressive loss of musclestrength and/or function associated with skeletal muscle fibrosis in asubject. Optionally and preferably, such at least reduction of theprogressive loss of muscle strength and/or function and/or treatmentand/or prevention occurs in a subject suffering from skeletal musclefibrosis associated with a disease of which directly or indirectlycauses such fibrosis, including but not limited to muscular dystrophy ordenervation atrophy. Muscular dystrophy includes Duchenne MuscularDystrophy; Becker Muscular Dystrophy; Emery-Dreifuss Muscular Dystrophy;Limb-Girdle Muscular Dystrophy; Facioscapulohumeral Muscular Dystrophy(also known as Landouzy-Dejerine); Myotonic Dystrophy; OculopharyngealMuscular Dystrophy; Distal Muscular Dystrophy; and Congenital MuscularDystrophy.

Unexpectedly, according to preferred embodiments of the presentinvention, a quinazolinone derivative, preferably halofuginone, mayoptionally and preferably be used to at least delay the progression offibrosis of the diaphragm in a subject suffering from a disease whichaffects this involuntary muscle, including but not limited to Duchennemuscular dystrophy. More preferably, the present invention relates totreating and/or preventing fibrosis of the diaphragm in a subjectsuffering from such a disease.

According to preferred embodiments of the present invention and asdemonstrated below, one or more types of muscle cells may optionally andpreferably be able to regenerate themselves as a result ofadministration of a quinazolinone derivative, preferably halofuginone,to a subject in need thereof.

The principles and operation of the compositions and methods accordingto the present invention may be better understood with reference to thedrawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details set forth in the following description or exemplified bythe Examples. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

Myostatin is a transforming growth factor-β (TGF-β) family member thatplays an essential role in regulating skeletal muscle growth, byinhibition of the proliferation and differentiation of myeloblasts, viainhibition of muscle-specific MyoD and myogenin genes. Signaling occursvia activation of Smad3 proteins (Langley, et al. (2002) J Biol Chem.277:49831-40 and Zhang, et al. (2000) J. Biol. Chem. 275:39237-45 andZhu, et al. (2004) Cytokine. 26(6):262-72; FIG. 1).

TGFβ is the major stimulator of collagen synthesis, particularlycollagen type I, in fibroblasts leading to fibrosis. The inversecorrelation between fibrosis and muscle formation in dystrophy has beendemonstrated (Wanger, et al. (2002) Ann Neurol. 52:832-6).

It has been demonstrated that halofuginone, an inhibitor of Smad3activity (McGaha, et al. (2002) J Invest Dermatol. 118(3):461-70), is apotent inhibitor of fibrosis due to its effect on collagen biosynthesisand degradation in variety of tissues (Levi-Schaffer, et al. (1996) JInvest Dermatol 106:84-88). The tissue types studied did not includeskeletal muscle. Furthermore, the prior art does not teach the use ofhalofuginone in regeneration of muscle.

Preliminary experiments by the present inventors have demonstrated ahalofuginone-dependent inhibition in myostatin gene expression infibrotic liver. Halofuginone is to date the only known collagentype-specific inhibitor on the transcriptional level. Inhibition ofcollagen synthesis on the transcriptional level is more effective thanattempting to treat the consequences of collagen overproduction, whichis the aim of other antifibrotic drugs.

Due to the numerous structural and functional differences betweenvarious muscle types, the effect of an active pharmaceutical ingredienton a particular muscle type cannot be predicted with any degree ofreliability.

Therefore, it was hypothesized that halofuginone may improve skeletalmuscle integrity and inhibit fibrosis in a subject, as a consequence ofits combined effect on inhibition of collagen type I synthesis, increasein collagen degradation and improved muscle regeneration by inhibitingTGFβ and myostatin Smad3-dependent pathways, as shown in FIG. 1. Also,halofuginone may inhibit myostatin gene expression in muscle as well aswas shown in other tissues causing a further increase in muscleregeneration.

Hereinafter, the term “halofuginone” is defined as a compound having theformula:

and pharmaceutically acceptable salts thereof.

The phrase “pharmaceutically acceptable salt” refers to a chargedspecies of the parent compound and its counter ion, which is typicallyused to modify the solubility characteristics of the parent compoundand/or to reduce any significant irritation to an organism by the parentcompound, while not abrogating the biological activity and properties ofthe administered compound.

Although the specific quinazolinone derivative “halofuginone” isreferred to throughout the specification, it is understood that otherquinazolinone derivatives may be used in its place, these derivativeshaving the general formula:

wherein: n=1-2R₁ is a member of the group consisting of hydrogen, halogen, nitro,benzo, lower alkyl, phenyl and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy and loweralkoxy; andR₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl, and pharmaceutically acceptable salts thereof.

The terms “skeletal muscle fibrosis” “muscle fibrosis” and “fibrosis” asused herein refer to a phenomenon that frequently occurs in diseased ordamaged muscle, characterized by the excessive growth of fibrous tissue,and impairment of muscle function.

Hereinafter, the term “a subject” refers to a human or animal to whomhalofuginone was administered.

The term “reducing the extent of” includes both substantially preventingthe process of skeletal muscle fibrosis from starting and slowing orhalting the progression of skeletal muscle fibrosis once it has arisen.

Compounds which are intended for the inhibition of skeletal musclefibrosis were tested by an in vivo model for their ability to slow orhalt the pathological process leading to deposition of fibrotic tissue.Such experiments were conducted for the collagen type I synthesisinhibitor halofuginone, as described in greater detail in the Examplessection below.

The mdx mouse was selected as a model to evaluate the efficacy ofhalofuginone in prevention and treatment of dystrophy by inhibitingmuscle fibrosis (by decreasing collagen synthesis and increasingcollagen degradation) and delaying muscle degeneration, and in improvingmuscle regeneration by inhibiting myostatin signaling.

As shown in the Examples section below, halofuginone was shown to behighly effective in reducing the extent of skeletal muscle fibrosis, andin improving skeletal muscle regeneration, in both skeletal muscle andin muscles of the diaphragm.

The present invention therefore provides a pharmaceutical compositioncomprising a quinazolinone derivative, such as halofuginone, forreducing the extent of skeletal muscle fibrosis and for improvingskeletal muscle regeneration.

The pharmaceutical composition of the present invention comprises, inaddition to the quinazolinone derivative, a pharmaceutically acceptablecarrier, and may optionally further comprise one or morepharmaceutically acceptable excipients, such as, for example, bindingagents, stabilizers, diluents, surfactants, flavors, and odorants.

Pharmaceutically acceptable carriers can be sterile liquids, such aswater and oils, including those of petroleum, animal, vegetable orsynthetic origin, such as peanut oil, soybean oil, mineral oil, sesameoil and the like. Water is a preferred carrier when the pharmaceuticalcomposition is administered intravenously. Saline solutions and aqueousdextrose and glycerol solutions can also be employed as liquid carriers,particularly for injectable solutions.

Pharmaceutical compositions of the present invention may be manufacturedby processes well known in the art, e.g., by means of conventionalmixing, dissolving, granulating, dragee-making, levigating, emulsifying,encapsulating, entrapping or lyophilizing processes. Further techniquesfor formulation and administration of active ingredients may be found in“Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa.,latest edition, which is incorporated herein by reference as if fullyset forth herein. Pharmaceutical compositions for use in accordance withthe present invention thus may be formulated in conventional mannerusing one or more pharmaceutically acceptable carriers comprisingexcipients and auxiliaries, which facilitate processing of the activeingredients into preparations which, can be used pharmaceutically.Proper formulation is dependent upon the route of administration chosen.

The pharmaceutical composition of the present invention may beadministered by any route selected from the oral, parenteral,transdermal, intravenous, subcutaneous, intramuscular, intranasal,intraauricular, sublingual, rectal, transmucosal, intestinal,intraauricular, buccal, intramedullar, intrathecal, directintraventricular, intraperitoneal, or intraocular routes. Preferably,administration is by the oral or parenteral routes.

Hereinafter, the term “oral administration” includes, but is not limitedto, administration by mouth for absorption through the gastrointestinaltract, buccal administration and sublingual administration.

For oral administration, the active ingredients can be formulatedreadily by combining the active ingredients with pharmaceuticallyacceptable carriers well known in the art. Such carriers enable theactive ingredients of the invention to be formulated as tablets, pills,dragees, capsules, liquids, gels, syrups, slurries, powders or granules,suspensions or solutions in water or non-aqueous media, and the like,for oral ingestion by a patient. Pharmacological preparations for oraluse can be made using a solid excipient, optionally grinding theresulting mixture, and processing the mixture of granules, after addingsuitable auxiliaries if desired, to obtain tablets or dragee cores.Suitable excipients such as thickeners, diluents, flavorings, dispersingaids, emulsifiers, binders or preservatives may be desirable.

Dragee cores are provided with suitable coatings. For this purpose,concentrated sugar solutions may be used which may optionally containgum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethyleneglycol, titanium dioxide, lacquer solutions and suitable organicsolvents or solvent mixtures. Dyestuffs or pigments may be added to thetablets or dragee coatings for identification or to characterizedifferent combinations of active ingredient doses.

Pharmaceutical compositions, which can be used orally, include push-fitcapsules made of gelatin as well as soft, sealed capsules made ofgelatin and a plasticizer, such as glycerol or sorbitol. The push-fitcapsules may contain the active ingredients in admixture with fillersuch as lactose, binders such as starches, lubricants such as talc ormagnesium stearate and, optionally, stabilizers. In soft capsules, theactive ingredients may be dissolved or suspended in suitable liquids,such as fatty oils, liquid paraffin, or liquid polyethylene glycols. Inaddition, stabilizers may be added. All formulations for oraladministration should be in dosages suitable for the chosen route ofadministration.

The term “parenteral administration” includes, but is not limited to,administration by intravenous drip or bolus injection, subcutaneous, orintra muscular injection. Formulations for parenteral administration maybe presented in unit dosage form, e.g., in ampoules or in multidosecontainers with optionally, an added preservative. The compositions maybe suspensions, solutions or emulsions in oily or aqueous vehicles, andmay contain formulatory agents such as suspending, stabilizing and/ordispersing agents.

Pharmaceutical compositions for parenteral administration includeaqueous solutions of the active preparation in water-soluble form.Additionally, suspensions of the active ingredients may be prepared asappropriate oily injection suspensions. Suitable lipophilic solvents orvehicles include fatty oils such as sesame oil, or synthetic fatty acidsesters such as ethyl oleate, triglycerides or liposomes. Aqueousinjection suspensions may contain substances, which increase theviscosity of the suspension, such as sodium carboxymethyl cellulose,sorbitol or dextran. Optionally, the suspension may also containsuitable stabilizers or agents which increase the solubility of theactive ingredients to allow for the preparation of highly concentratedsolutions.

The dosage may vary depending upon the dosage form employed and theroute of administration utilized. The exact formulation, route ofadministration and dosage can be chosen by the individual physician inview of the patient's condition. (See e.g., Fingl, et al., 1975, in “ThePharmacological Basis of Therapeutics”, Ch. 1 p. 1).

Compositions of the present invention may, if desired, be presented in apack or dispenser device, such as an FDA approved kit, which may containone or more unit dosage forms containing the active ingredient. The packmay, for example, comprise metal or plastic foil, such as a blisterpack. The pack or dispenser device may be accompanied by instructionsfor administration. The pack or dispenser may also be accompanied by anotice associated with the container in a form prescribed by agovernmental agency regulating the manufacture, use or sale ofpharmaceuticals, which notice is reflective of approval by the agency ofthe form of the compositions or human or veterinary administration. Suchnotice, for example, may be of labeling approved by the U.S. Food andDrug Administration for prescription drugs or of an approved productinsert.

Additional objects, advantages, and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting. Additionally, each of the various embodiments and aspects ofthe present invention as delineated hereinabove and as claimed in theclaims section below finds experimental support in the followingexamples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions, illustrate the invention in a non limiting fashion.

Example 1 Collagen Content and Collagen α1 (I) Gene Expression (in theQuadriceps and Tibialis Muscles

Mdx mice were treated either with halofuginone by I.P. injection everyother day (3 μg/mouse) starting at 5 weeks of age for 4 weeks, or withsaline vehicle. C57B mice were used as controls.

At the end of the 4 week period, tibialis anterior (fast) and quadriceps(slow) muscles were removed for evaluation of fibrosis by Sirius redstaining for collagen content, and by in situ hybridization of collagenα1(I) gene expression.

Example 2 Effect of Halofuginone on Fibrosis in the Diaphragm,Gastrochnemius and Tibialis Muscles

Halofuginone was administered by I.P injection to mdx mice (n=7) from 3weeks of age every other day at a concentration of 5 μg/mouse The wildtype (C57/BL) and mdx mice without halofuginone served as controls. Atthe age of 7 and 11 weeks the mice were sacrificed and the diaphragm,gastrochnemius and the tibialis were fixed for histology and sampleswere frozen for further analysis. Sections were stained for collagen bySirius red and with methyl green as a counter stain. Image analysisusing the Image Pro software was performed for statistical evaluation ofthe effect of halofuginone on collagen content. For the image analysis,images were taken from 3 animals/group and 4 replicates from eachanimal/tissue. The results are the ratio of red (R) to green color (G).

Example 3 Effect of Halofuginone on Muscle Regeneration

Mdx mice were treated with halofuginone 5 μg or 7.5 μg for 1 or 2 monthsstarting at age of 3 weeks. The untreated mdx mice served as controls.At the end of the experiment, the diaphragms were taken for hematoxyline& eosine staining before central nuclei counting. The results are themean±SE of 20 photos taken from 3 different mice. Each photo containedapproximately 120 fibers.

Results

As shown in FIG. 2, the quadriceps (slow) and tibialis (fast) muscles ofthe C57B controls showed almost no cells expressing the collagen α1(1)gene, and low levels of collagen surrounding the fibers were observed. Asignificant increase was observed both in the expression of collagen al(I) gene and in the amount of collagen fibers in the mdx quadriceps andtibialis muscles compared to the controls. This increase was almostcompletely prevented by halofuginone treatment.

FIG. 3 demonstrates that in the wild-type mice, the level of collagenwas low in diaphragm, gastrochnemius and tibialis whereas in the mdxmice, an increase in the collagen content was observed in all muscles.The main increase was observed in the diaphragm; this was alreadyevident at 3 weeks of age and reached 9 and 15-fold increase compared tothe wild type at 7 and 11 weeks, respectively. In the gastrochnemius, anincrease in the collagen content was observed already at 3 weeks of agewith further increase at 7 weeks. At older ages, a decline in thecollagen content was observed although the level was still higher thanthat in the wild type. Only a minute increase in collagen was observedin the tibialis. In the diaphragm, halofuginone reduced the collagenlevels by 25% at 7 weeks (4 weeks of treatment) and by 53% at 11 weeks(8 weeks of treatment). In the gastrochnemius, halofuginone reduced thecollagen content by 25% and 33% at 7 and 11 weeks, respectively. Noeffect of halofuginone on the collagen content was observed in thetibialis muscle.

FIG. 4 shows the effect of halofuginone 5 μg (purple) or 7.5 μg (offwhite) on muscle regeneration, with untreated mdx mice (blue) ascontrol. In the wild type mice, the nucleus of each muscle fiber islocated at the periphery of the cell. In the mdx mice small immaturecentrally nucleated fibers are observed, reflecting muscle regenerationfrom myoblasts that results in a balance between necrotic andregenerative processes in the early phase of the disease. Afterhalofuginone treatment a major reduction in the number of diaphragmcentral nuclei was observed that was dose-dependent. These resultssuggest that halofuginone improved the muscle physiology and reduced thepressure on the mdx mice muscle to regenerate.

DISCUSSION

In different muscular dystrophies and dystrophic syndromes, differentmuscle types are affected by fibrosis to a different extent. In the mdxmouse, which serves as a model for Duchenne muscle dystrophy (DMD), themost affected muscle is the diaphragm although other muscles are alsoaffected. Consequently, the greatest effect of halofuginone in mdx micewas shown with regard to fibrotic diaphragm muscles, resulting in 53%inhibition of fibrosis and of the fibrotic process.

Together, the above results suggest that halofuginone is a potentinhibitor of muscle fibrosis in mdx mice by inhibiting collagen type Isynthesis and may inhibit the need for muscle degeneration by inhibitingthe myostatin pathway.

The above results further show that the extent of inhibition of fibrosisby halofuginone is dependent upon the extent of fibrosis. Halofuginonehas been shown to inhibit fibrosis by inhibition of collagen synthesisin every muscle that is affected by fibrosis, but in muscles in whichonly minute increases in collagen synthesis occur, the inhibition ofcollagen synthesis caused by halofuginone may not be clearlydemonstrable in the context of the experiment, for example during thetime period tested.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention.

What is claimed is:
 1. A pharmaceutical composition for treating and/orpreventing skeletal muscle fibrosis in a subject in need thereof, thecomposition comprising a pharmaceutically effective amount of a compoundin combination with a pharmaceutically acceptable carrier, the compoundhaving a formula:

wherein: n is either 1 or 2 R₁ is a member of the group consisting ofhydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy, and loweralkoxy; and R₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl; and pharmaceutically acceptable salts thereof.
 2. Apharmaceutical composition according to claim 1, wherein said compoundis halofuginone.
 3. A pharmaceutical composition according to claim 1,wherein said subject is suffering from a disorder which encompassesskeletal muscle tissue.
 4. A pharmaceutical composition according toclaim 3, wherein said disorder is muscular dystrophy.
 5. Apharmaceutical composition according to claim 4, wherein said musculardystrophy is selected from the group consisting of Duchenne musculardystrophy, Becker muscular dystrophy, Emery-Dreifuss Muscular Dystrophy,Limb-Girdle Muscular Dystrophy, Facioscapulohumeral Muscular Dystrophy,Myotonic Dystrophy, Oculopharyngeal Muscular Dystrophy, Distal MuscularDystrophy, and congenital muscular dystrophy.
 6. A pharmaceuticalcomposition according to claim 3, wherein said disorder is denervationatrophy.
 7. A pharmaceutical composition according to claim 3, whereinsaid skeletal muscle tissue is diaphragm muscle.
 8. A pharmaceuticalcompositions for improving or inducing skeletal muscle regeneration in asubject in need thereof, the composition comprising a pharmaceuticallyeffective amount of a compound in combination with a pharmaceuticallyacceptable carrier, the compound having a formula:

wherein: n is either 1 or 2 R₁ is a member of the group consisting ofhydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy, and loweralkoxy; and R₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl; and pharmaceutically acceptable salts thereof.
 9. Apharmaceutical composition according to claim 8, wherein said compoundis halofuginone.
 10. A pharmaceutical composition according to claim 8,wherein said subject is suffering from a disorder which targets skeletalmuscle tissue.
 11. A pharmaceutical composition according to claim 10,wherein said disorder is muscular dystrophy.
 12. A pharmaceuticalcomposition according to claim 11, wherein said muscular dystrophy isselected from the group consisting of Duchenne muscular dystrophy,Becker muscular dystrophy, Emery-Dreifuss Muscular Dystrophy, LimbGirdleMuscular Dystrophy, Facioscapulohumeral Muscular Dystrophy, MyotonicDystrophy, Oculopharyngeal Muscular Dystrophy, Distal MuscularDystrophy, and congenital muscular dystrophy.
 13. A pharmaceuticalcomposition according to claim 10, wherein said disorder is denervationatrophy.
 14. A pharmaceutical composition according to claim 10, whereinsaid skeletal muscle tissue is diaphragm muscle.
 15. A method forreducing the progression of skeletal muscle fibrosis in a subject inneed thereof, the method comprising administering a pharmaceuticallyeffective amount of a compound in combination with a pharmaceuticallyacceptable carrier, the compound having a formula:

wherein: n is either 1 or 2 R₁ is a member of the group consisting ofhydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy, and loweralkoxy; and R₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl; and pharmaceutically acceptable salts thereof.
 16. Amethod according to claim 15, wherein said compound is halofuginone. 17.A method according to claim 15, wherein said subject is suffering from adisorder which targets skeletal muscle tissue.
 18. A method according toclaim 17, wherein said disorder is muscular dystrophy.
 19. A methodaccording to claim 18, wherein said muscular dystrophy is selected fromthe group consisting of Duchenne muscular dystrophy, Becker musculardystrophy, Emery-Dreifuss Muscular Dystrophy, Limb-Girdle MuscularDystrophy, Facioscapulohumeral Muscular Dystrophy, Myotonic Dystrophy,Oculopharyngeal Muscular Dystrophy, Distal Muscular Dystrophy, andcongenital muscular dystrophy.
 20. A method according to claim 17,wherein said disorder is denervation atrophy.
 21. A method according toclaim 17, wherein said skeletal muscle tissue is diaphragm muscle.
 22. Amethod for improving or inducing skeletal muscle regeneration in asubject in need thereof, the method comprising administering apharmaceutically effective amount of a compound in combination with apharmaceutically acceptable carrier, the compound having a formula:

wherein: n is either 1 or 2 R₁ is a member of the group consisting ofhydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy, and loweralkoxy; and R₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl; and pharmaceutically acceptable salts thereof.
 23. Amethod according to claim 22, wherein said compound is halofuginone. 24.A method according to claim 22, wherein said subject is suffering from adisorder which targets skeletal muscle tissue.
 25. A method according toclaim 24, wherein said disorder is muscular dystrophy.
 26. A methodaccording to claim 25, wherein said muscular dystrophy is selected fromthe group consisting of Duchenne muscular dystrophy, Becker musculardystrophy, Emery-Dreifuss Muscular Dystrophy, Limb-Girdle MuscularDystrophy, Facioscapulohumeral Muscular Dystrophy, Myotonic Dystrophy,Oculopharyngeal Muscular Dystrophy, Distal Muscular Dystrophy, andcongenital muscular dystrophy.
 27. A pharmaceutical compositionaccording to claim 24, wherein said disorder is denervation atrophy. 28.A pharmaceutical composition according to claim 24, wherein saidskeletal muscle tissue is diaphragm muscle.
 29. A method according toclaim 22, wherein the improving of skeletal muscle regeneration occursthrough inhibiting the TGFβ pathway and/or by inhibiting the MyostatinSmad3-dependent pathway.
 30. Use of a compound having a formula:

wherein: n is either 1 or 2 R₁ is a member of the group consisting ofhydrogen, halogen, nitro, benzo, lower alkyl, phenyl, and lower alkoxy;R₂ is a member of the group consisting of hydroxy, acetoxy, and loweralkoxy; and R₃ is a member of the group consisting of hydrogen and loweralkenoxy-carbonyl; and pharmaceutically acceptable salts thereof; in themanufacture of a medicament for reducing the progression of skeletalmuscle fibrosis in a subject in need thereof.
 31. The use according toclaim 30, wherein said compound is halofuginone.
 32. The use accordingto claim 30, wherein said subject is suffering from a disorder whichtargets skeletal muscle tissue.
 33. The use according to claim 32,wherein said disorder is muscular dystrophy.
 34. The use according toclaim 33, wherein said muscular dystrophy is selected from the groupconsisting of Duchenne muscular dystrophy, Becker muscular dystrophy,Emery-Dreifuss Muscular Dystrophy, Limb-Girdle Muscular Dystrophy,Facioscapulohumeral Muscular Dystrophy, Myotonic Dystrophy,Oculopharyngeal Muscular Dystrophy, Distal Muscular Dystrophy, andcongenital muscular dystrophy.
 35. The use according to claim 32,wherein said disorder is denervation atrophy.
 36. The use according toclaim 32, wherein said skeletal muscle tissue is diaphragm muscle.